1. Field of the Invention
The present invention relates generally to angiographic catheters used to access a blood vessel, and more particularly, to devices for sealing the external end of an angiographic catheter or needle following insertion of such devices into the vascular system.
2. Description of the Prior Art
Catheters and needles are inserted into the vascular system for many reasons including, diagnosis, therapy or to draw blood samples. During an angiographic procedure, a catheter is placed into the vascular system commonly using a Seldinger technique. This technique consists of placing a needle percutaneously into a blood vessel of the vascular system, and then threading a flexible guidewire through the lumen of the needle into the blood vessel. The guidewire is left in place within the blood vessel, and the needle is thereafter removed. The distal tip of the catheter is then threaded over the external end of the guidewire and advanced therealong and positioned within the vascular system in accordance with the prior placement of the guidewire; the guidewire is thereafter removed. Diagnostic fluids may then be injected into the blood vessel to diagnose or treat various vascular conditions.
The steps described above must often be repeated during a procedure in order to manipulate the catheter, i.e., to move the catheter into various branches of the vascular system. To perform such manipulation, the guidewire is reinserted into the catheter, and the guidewire and catheter are then manipulated to the new position.
The angiographic catheter includes a fluid-communicating lumen extending between the distal end and proximal end thereof. Upon introduction of the distal end of the catheter into the blood vessel, blood pressure within the body forces blood into the catheter lumen. Some blood may escape from the proximal end of the catheter even before the guidewire is removed by flowing through the annulus between the guidewire and the inner walls of the catheter. Once the guidewire is withdrawn from the catheter, the outward flow of blood through the lumen of the catheter is essentially unimpeded.
Physicians prefer to minimize the amount of blood leakage from angiographic catheters for two compelling reasons. First, it is important to prevent blood loss from the patient to avoid the need for blood transfusions. Secondly, blood may contain highly infectious material such as hepatitis or AIDS to which medical personnel are exposed, and it is therefore beneficial to medical personnel to limit blood loss.
In order to prevent blood from freely draining out of the angiographic catheter, a first port of a stopcock is commonly secured by means of a luer lock connection to the proximal end of the catheter external to the patient. Such stopcocks are well known and include a manually rotatable handle or lever operated by the thumb and forefinger for selectively opening or sealing the proximal end of the catheter. Such stopcocks typically include a second port, also provided with a luer lock connection fitting, in fluid communication with the first port thereof when the stopcock is open. In order to draw blood from the patient into a syringe, or to inject a substance into the blood vessel through the catheter, the stopcock must be turned by hand into the opened position. When the catheter is not being used to perform aspiration or infusion, it is standard medical practice to inject heparinized saline through the catheter while closing the stopcock. This anticoagulant solution flushes any blood from the catheter and thereafter prevents blood from entering the catheter and clotting inside.
As described above, during vascular procedures involving catheters, it is common to pass a guidewire into the proximal end of the catheter to help guide the catheter tip into a selected blood vessel. If a stopcock has been secured to the proximal end of the catheter, then the stopcock must first be opened so that the distal tip of the guidewire may be passed through the opened stopcock into the catheter. When the stopcock is opened, the heparinized saline that was previously injected into the catheter is flushed out by the blood. The guidewire is passed into the catheter which now contains stagnant blood which can form blood clots between the guidewire and the inner wall of the catheter. Moreover, during guidewire manipulations, the stopcock must be left open to permit passage of the guidewire; accordingly, blood can flow between the guidewire and inner lumen of the catheter, and often drips out at the second port of the stopcock. This slow flow of escaping blood may form clots within the catheter; these blood clots can be forced back into the vascular system when the guidewire is advanced or when subsequent injections are made through the catheter. Introduction of such blood clots can result in blocked blood vessels; if these blood vessels are critical, for example, the coronary arteries, it is possible that permanent, severe damage can occur.
Thus, while conventional stopcocks help to reduce the outflow of blood through angiographic catheters, they are only partially effective. Blood often flows out of a stopcock when opened for a guidewire to pass through it, or when a connection is made to a syringe or an infusion line. Moreover, conventional stopcocks are cumbersome because they often require two hands for operation. One hand holds the stopcock while the other turns the lever. This maneuver may be difficult for a physician to achieve, particularly when, for example, one of the physician's hands is needed to maintain the position of the catheter.
Another problem related to stopcocks arises when a catheter that has been fitted with a stopcock must be attached to a power injector, for example, when a large quantity of x-ray dye is to be injected while obtaining radiographs to visualize the blood vessel. The physician sometimes forgets to turn the stopcock into the opened position, in which case the dye is prevented from entering the catheter. The radiographs are obtained but do not provide the desired diagnostic information because the dye was not injected. The patient is therefore unnecessarily exposed to radiation, and the procedure must be repeated by the physician a second time to obtain the desired diagnostic information.
Apart from conventional stopcocks, other devices are known for reducing blood loss through angiographic catheters. For example, a variety of hemostasis valves are known which may be secured to the proximal end of an angiographic catheter to minimize blood loss around a guidewire that is positioned within a catheter, while permitting fluid to be injected into the catheter with the guidewire in place. One example of such a hemostasis valve is available from Cordis Corporation of Miami, Fla. under the product name "Adjustable Hemostasis Valve", Catalog No. 501-622. Such device includes a male luer lock connection fitting for being secured over the proximal end of an angiographic catheter. The device also includes a rotatable barrel which can be manually rotated to adjust the degree of compression exerted upon an annular compression washer. A guidewire may be inserted through the central opening in the rotatable barrel and passed into the proximal end of the catheter. The barrel can then be manually rotated to tighten the compression washer to form a seal about the guidewire. The device also includes a sideport extension with a luer lock fitting to permit flushing and/or infusion of fluids. However, such device must be manipulated by the physician to adjust the degree to which the compression washer seals against the walls of the guidewire. In addition, if the guidewire is to be removed, the device must again be manually rotated, first to release the guidewire, and thereafter to reseal the guidewire passage. As noted above, the physician's hands are often required for other purposes. A similar type of device is also available under the product name "Tuohy-Borst Adapter" from Universal Medical Instrument Corp. of Ballston Spa, New York; the latter device includes a sideport extension through which a high pressure injection of fluid may be made while the guidewire is clamped therein.
Another device which has been introduced to avoid leakage of blood from angiographic catheters is available from Medi-tech, Incorporated of Watertown, Mass. under the product name "FloSwitch HP" Catalog No. 44-200. This product resembles the device described within U.S. Pat. No. 4,243,034 issued to Brandt, and is further described in Widlus, "Technical Note: Safety of High Pressure Injections Through a Flow Switch Stopcock", CardioVascular and Interventional Radiology (1988) 11:307-308. The device includes a male luer connector at one end for being secured to the proximal end of the catheter, and includes an opposing end provided with a female luer connector for allowing a syringe to be secured thereto. The device includes a sliding thumb switch which may be opened or closed with or without a guidewire in place. If a guidewire is passed through such device, the slide switch may be advanced toward the closed position until the movable sealing member engages the wall of the guidewire to minimize blood leakage. While representing an improvement over a conventional stopcock or simple hemostasis valve, the "FloSwitch HP" flow control device still requires manual operation by the physician, and still allows a physician to forget that he has left the switch in the closed position when attempting to inject dye into the catheter.
Hemostasis valves using deformable elastomeric seals are widely known for use within catheter introducer sheaths. Such catheter introducer sheaths are available from a variety of manufacturers, including the catheter sheath introducer available from Cordis Corporation of Miami, Fla. under the product name "Catheter Sheath Introducer", Catalog No. 501-675U. Patents generally directed to such catheter introducer sheaths include U.S. Pat. No. 4,610,665 (Matsumoto et al.); U.S. Pat. No. 4,626,245 (Weinstein); U.S. Pat. No. 4,000,739 (Stevens); U.S. Pat. No. 4,430,081 (Timmermans); and U.S. Pat. No. 4,673,393 (Suzuki et al.). While such introducer sheaths are effective in preventing blood loss which would otherwise result when a catheter or guidewire is inserted therethrough, such devices do not solve the problem of preventing blood loss from the proximal end of an angiographic catheter of the type used to inject fluids under high pressure within the vascular system.
Finally, a variety of devices are known which include deformable elastomeric seals that are adapted to form a fluid seal but which are deformed upon insertion of the tip of a syringe or other conical member to permit fluid flow therethrough. Examples of such devices are described within U.S. Pat. No. 3,837,381 (Arroyo); U.S. Pat. No. 4,143,853 (Abramson); U.S. Pat. No. 4,387,879 (Tauschinski); U.S. Pat. No. 4,765,588 (Atkinson); U.S. Pat. No. 4,842,591 (Luther); and United Kingdom Patent No. 2,067,075 (Krutten et al.). In particular, the patent to Abramson describes a check valve for use with a catheter or needle and including a slit rubber disc supported in a housing having a first male connection having a standard luer-type taper and having a second luer-type female connection. The valve device is described for use in conjunction with a needle having a luer-type female fitting for withdrawing blood samples. Blood samples are withdrawn by inserting into the female connection of the check valve the tip of a syringe having a male connector at its tip to spread apart the slit in the valve. However, no suggestion is made in such disclosure of the use of such a check valve in conjunction with an angiographic catheter, or for passage of a guidewire therethrough.
The above-mentioned patent to Tauschinski discloses a self-sealing connector for coupling a vein catheter to a supply of blood or parenteral solution. The described device includes a slit elastic disc to selectively seal the flow of fluid. In at least one embodiment, an axially slidable member having a central bore is advanced into contact with the slit disc to open the same when the end of a supply hose is inserted into one of the ports of the device. Once again, no suggestion is made that such a device is capable of being used in conjunction with an angiographic catheter, that a guidewire be passed through the elastic disc, or that such a device is adapted for high pressure injections of fluid into an angiographic catheter.
The above-mentioned patent to Atkinson discloses a check valve for coupling a syringe to a fluid supply container for allowing a user to withdraw fluid from the supply container into the syringe. The check valve includes a slit elastomeric diaphragm. Insertion of the distal end of the syringe into the check valve causes such distal end to push through the slit diaphragm.
The above-mentioned patent to Luther describes a one-way valve connector for coupling a syringe tip to a catheter. The one-way valve includes a resilient slit septum that can be deformed by a movable plug. Insertion of the syringe tip causes the plug to move forwardly to deform the septum for allowing liquid to be injected therethrough. Again, no suggestion is made that such a check valve may be used with an angiographic catheter, or that a guidewire be passed through the slit of the resilient septum.
In addition, U.S. Pat. No. 3,601,151 to Winnard discloses a one way valve which, in one embodiment, is coupled between a needle inserted into a vein and a syringe used to withdraw blood samples. Such device does not include a slit seal and is not adapted to permit passage of a guidewire therethrough.
Accordingly, it is an object of the present invention to provide a device which can be secured to an angiographic catheter to prevent and/or minimize the loss of blood from the proximal end of such catheter following placement of the catheter within a blood vessel.
Another object of the present invention is to minimize blood loss from an angiographic catheter when inserting a guidewire therein.
Another object of the present invention is to provide such a device which permits a guidewire to be freely passed through an angiographic catheter while providing a seal around the guidewire to prevent any blood from passing between the guidewire and catheter while the guidewire is present.
Another object of the present invention is to prevent or minimize blood loss from an angiographic catheter when connecting or disconnecting a syringe or infusion line thereto.
Still another object of the present invention is to provide such a device which permits a syringe to be coupled to the proximal end of the catheter while effecting a fluid-tight, high-pressure seal therebetween.
Yet another object of the present invention is to provide such a device which does not require any manipulation of levers or switches in order to pass a guidewire into the proximal end of the catheter, and which similarly does not require any manipulation of levers or switches in order to inject or aspirate a fluid therethrough.
A further object of the present invention is to provide such a device which prevents heparinized saline or other anticoagulant fluid from being flushed out of the catheter when a syringe or fluid line is uncoupled from the proximal end of the catheter or when a guidewire is inserted into the catheter.
A still further object of the present invention to provide such a device which is of simple and inexpensive construction.
Another object of the present invention is to provide such a device which automatically opens when a syringe or other medical injection line is attached to it; similarly, when the syringe or injection line is removed therefrom, the device automatically closes without any intervention by the physician.
These and other objects of the invention will become more apparent to those skilled in the art as the description of the invention proceeds.